Burning mouth syndrome

Oh, that is sooo painful! I hated mine, even though it was not near as bad as it sounds like yours is. I'm glad mine is gone except when my B12 vials are late.

I know you said you're just looking for someone to talk to about it but it sounds like you're doing all you can to make it go away. So, here i go, asking questions you've probably been asked 100x's before and giving unsolicited advice. Please note i am not a medical pro of any kind, except for being a patient who has been mis/undiagnosed, blown off, gaslit, had my intelligence insulted etc. by many doctors and specialists so I may be slightly biased. This is just my personal experience.

Do you have any other symptoms like poor balance, pins and needles anywhere but esp the bottom of your feet, fatigue, Raynaud's, shooting/cramping pains, divits in your finger/toenails, and do you know your hemoglobin, hematocrit ferritin and folate levels?
I'm sure you know this but just in case...
Burning mouth syndrome can be associated with both iron deficiency anemia (IDA, which also usually has smaller, immature red blood cells as well as fewer of them) and B12 deficiency, (with or without enlarged red blood cells, associated with pernicious anemia [PA] usually Dx'd bc megabolastic anemia).
IDA + PA can cancel each other out under the microscope, making your red blood cells look normal sized.

When i had burning mouth syndrome, it cleared up when i finally got Dx'd and started the B12 protocol as described on the facebook group page 'Vitamin B12 Wake Up'. You can visit B12d.org and download a whole book on the subject. Unfortunately, the founder passed away a couple years ago and the site is not as well maintained as it once was, but the book is still available for download and it's still a very informative site. You can also go to YouTube and watch the movie "Could It Be B12". It's old and cheesy but super interesting if that happens to be your issue.
It's also in audio, ebook or print.

1st things 1st though. Don't take any supplements or drink any energy drinks or meal shakes for several weeks then get a methylomonic acid test (MMA) and if it's slightly elevated, suspect B12 deficiency. If not taking/drinking anything with B12 or folate in it is unrealistic for you, just ask for a B12 shot and within 1 to 4 days (depending on the form of B12 used) you should be able to feel a difference in the above symptoms, and if it turns out to be the problem, symptoms should start to dissappear from most recent to oldest presentation.

B12 is a water soluble vitamin, so although you can have really high amounts in your blood (serum B12) it generally doesn't do any harm.

B12 deficiency is, IMO, not well understood, tested for, or treated like it used to be. I guess it had its moment in the sun, just like vitamin C and D had their moments...15 minutes of fame and all that. Leave no stone unturned. Whatever it is, i hope you get it Dx'd and treated a.s.a.p.